Pseudoporphyria Clinical Presentation

Updated: May 11, 2018
  • Author: Vineet Mishra, MD, FAAD; Chief Editor: Dirk M Elston, MD  more...
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Presentation

History

A careful history is of utmost importance when the diagnosis of pseudoporphyria is being considered. A personal and family history of hepatitis, porphyria, connective-tissue disease, or other photosensitivity disorders must be sought. In addition to reviewing a patient’s medication list, it is also important to elicit a thorough history of over-the-counter agents, including herbs and supplements, taken by a patient as such agents may provide diagnostic clues.

Although a genetic factor has not been considered in pseudoporphyria, one case of monozygotic twins developing pseudoporphyria after excessive UV-A exposure from long-term tanning bed use has been documented. [5]

The patient should be thoroughly questioned regarding any symptoms of connective tissue disorder, which may be the underlying pathology of the photosensitivity. Some reports suggest that a connective-tissue disorder may be a predisposing factor in patients using nonsteroidal anti-inflammatory drugs (NSAIDs) who develop pseudoporphyria.

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Physical Examination

Pseudoporphyria is clinically characterized by increased skin fragility; erythema; and the appearance of tense bullae and erosions on sun-exposed skin (see image below), which are identical to those seen in patients with porphyria cutanea tarda.

Pseudoporphyria. Courtesy of DermNet New Zealand ( Pseudoporphyria. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/reactions/pseudoporphyria1.jpg).

However, a clinical pearl that may prove helpful in differentiating between pseudoporphyria and porphyria cutanea tarda is that the classic features of hypertrichosis, hyperpigmentation, and sclerodermoid changes found with porphyria cutanea tarda are unusual with pseudoporphyria. Additionally, those patients who develop pseudoporphyria in association with the use of tanning beds may develop lesions on the palmar surfaces, which are usually not subject to UV exposure. [69] Of note, while pseudoporphyria may occur in isolation, it may also present with concomitant dermatoses that are commonly seen in patients with renal disease, such as xerosis and acquired reactive perforating collagenosis. [70]

A second clinical pattern of pseudoporphyria has a similar presentation to erythropoietic protoporphyria (EPP), an autosomal dominant porphyria resulting from a reduced activity of ferrochelatase. In contrast to porphyria cutanea tarda, erythropoietic protoporphyria usually begins in childhood with a history of photosensitivity, often described as a burning sensation immediately after sunlight exposure. Clinically, erythropoietic protoporphyria is characterized by erythema, edema, shallow scars, and waxy induration of the skin, particularly on the face. Pseudoporphyria that clinically mimics erythropoietic protoporphyria has been described almost exclusively in children taking naproxen for juvenile rheumatoid arthritis. [71] Naproxen-induced pseudoporphyria seems to have a dimorphic presentation with the porphyria cutanea tarda–like pattern more often seen in the adult population and the erythropoietic protoporphyria–like pattern more commonly seen in children, although some overlap has been documented.

A single case of a rare and atypical variant of pseudoporphyria has also been reported to present with tender, indurated plaques on the abdomen and flanks that became necrotic, as well as 1- to 2-cm tense bullae on non–sun-exposed locations (genitals, medial thighs) that rapidly enlarge up to 15 cm, leaving large denuded areas that clinically resembled toxic epidermal necrolysis. [72] Despite the clinical presentation of this case, Nikolsky sign was negative and multiple skin biopsies demonstrated the findings of paucicellular subepidermal blisters with festooning of dermal papillae that are associated with lesions of porphyria or pseudoporphyria.

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